ECMASCript feature

Implement Symbol.prototype[ @@toPrimitive ]( hint ).

The to primitive function described in spec can be created with FunctionBuilder and it can be added to Symbol.prototype with ConstructorBuilder::property() method.

#1263

Todoのlistにulが抜けているためスタイルがおかしくなっている

might be something simple, like not using forceSelection for change events.

Need to verify and update the tsdocs links to include all the new generated modules.